Breast reconstruction is one of the most common procedures performed in plastic surgery today. One out of eight women will have breast cancer in their lifetime, the majority of whom will undergo reconstruction. Currently federal law mandates that any woman who has breast cancer must be offered reconstruction. Last year 96,000 breast reconstructions were performed, the vast majority of which were expander implant based reconstructions. Of note, many cases are bilateral, and therefore over 100,000 expanders are being utilized in breast reconstruction ever year.
The typical breast reconstruction process involves placing a deflated tissue expander in the chest pocket after mastectomy (breast removal). The expander includes a port through which sterile saline can be forced, causing the volume of the expander to increase. The expander is usually filled with sterile saline in the operating room prior to closing the surgical opening in the skin. The patient then returns to the clinic two weeks later for further expansion. Because the port is covered by skin, the port is located with the aid of a port locator magnet. Once it is located, a needle is placed through the skin into the port and sterile saline is injected. This procedure is done on a weekly basis until the skin envelope is expanded to a large enough size to accommodate the desired implant size for an appropriately sized breast mound. Typically, the expansion procedure is performed four to eight separate times prior to being ready for the expander/implant exchange.
This procedure is not limited to breast reconstruction. Tissue expanders are also used in burn reconstruction and various other types of reconstruction where skin expansion is needed.
The most pressing issue associated with breast and other types of tissue expansion is the exceedingly narrow needle used in current systems, such as the MENTOR brand winged infusion set, as compared to the pipe diameter of the rest of the system. The entire system is bottlenecked by the 21 gauge needle that is used to inject the port. The inner diameter of the needle is 0.51 mm (outer diameter 0.81 mm), which is the maximum allowable gauge needle per the manufacturer instructions (see Mentors Product Website) due to the nature of the port. Narrow needles result in slow flow of sterile saline, and require more time to fill the tissue expander. The filling process in the operating room can be as long as 10 to 15 minutes during which time the surgeons and nurse must patiently wait for the expander to fill with the patient still open. Simply a larger needle would core out the silicone and make the port leak, and thus fail.